Epidural Beats Remifentanil for Pain Relief

Action Points

This study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Remifentanil -- a synthetic opioid with a rapid onset of action -- used as patient-controlled analgesia for women in labor did not produce as much pain relief as epidural analgesia in a randomized controlled trial.

NEW ORLEANS -- Remifentanil patient-controlled analgesia (RPCA), which has been reported to have equal pain relief to epidural analgesia (EA) in previous studies, did not match pain relief from EA, researchers reported here.

After the start of pain relief, time-weighted pain appreciation (a measure of satisfaction with pain relief) among women in the RPCA group only reached 25.7 compared with women who received EA and peaked at 36.8 (mean difference 11.1 95% CI 7.5-14.7, P<0.001), Liv Freeman, MD, of Leiden University Medical Centre in the Netherlands, and colleagues reported at the annual meeting of the Society of Maternal-Fetal Medicine.

Freeman told MedPage Today that it's difficult to say whether remifentanil is safer than epidural analgesia (EA), because there are often side effects with epidurals generally. "We've used EA much longer, so we're more sure about the side effects. With remifentanil, you can have respiratory depression and low oxygen, and that happens more often in women that do have remifentanil."

Remifentanil is a rapidly metabolized synthetic opioid with a rapid onset of 1-3 minutes for peak effect.

Because remifentanil does not require application by an anesthesiologist, like EA, Freeman told MedPage Today that in the Netherlands, patients often choose to give birth at one of the hospitals, roughly half of those in the country, that offer remifentanil as a pain relief option, since "it's less invasive than EA and they can control it themselves."

Freeman also noted that a side effect of EA is hypotension, which can affect fetal heart rate and result in emergency C-section. EA can also cause a spike in temperature, which raises suspicion of infection in the neonate and can send the baby to the neonatal intensive care unit. "Both are relatively safe, but both have their own side effects, so you have to monitor it very carefully and balance out what risk you are willing to take."

"Even though it's [remifentanil] not equivalent to epidural analgesia, it gives pain relief .... The women that labor longer are the women that convert to EA or increase their doses of remifentanil," Freeman told MedPage Today.

"I think you need a good protocol for monitoring remifentanil. I recommend one-to-one nursing, at least within the first hour, and monitoring respiratory rate and oxygen saturation. And counsel patients that it [remifentanil] gives pain relief, but that if they want superior pain relief and want to be really satisfied, they should take the EA. If they want pain relief which is maybe less invasive and they can control themselves, I think remifentanil for a shorter period of time is a good option," Freeman said.

For the trial, an IV RPCA bolus 30 mcg with a 3-minute lockout with an option for 40 mcg was available for 687 women, and EA was available for 671 women, across 15 hospitals in the Netherlands. The visual analog scale was used for the mothers to report pain levels.

Women in the RPCA group were more likely to choose pain relief overall (65.1%) compared with women in the EA group (51.7%, P<0.001). The time from request to start of administration was much shorter for RPCA at 28 minutes (range 14-45) compared with EA at 55 minutes (range 32-80, P<0.001).

Duration of pain relief was shorter for RPCA at 236 minutes (range 128-376) compared with 309 for EA (range 181-454, P<0.001). C-section rates were similar among RPCA and EA women (15.4% versus 14.9%).

During active labor, time-weighted pain appreciation among RPCA women was 30.5 versus 34.2 among EA women (mean difference 3.7 95% CI -7.6-0.3, P=0.067). After the start of pain relief, pain appreciation among women in the RPCA group was 25.7, and 36.8 among women in the EA group (mean difference 11.1 95% CI 7.5-14.7, P<0.001).

"You see a significantly lower [oxygen] saturation, more low saturation with women using remifentanil," Freeman said. Oxygen saturation lower than 95% occurred in 37.1% of women on RPCA compared with only 12.3% of women with an EA (risk ratio 1.63 95% CI 1.46-1.82, P<0.001). Oxygen saturation less than 92% occurred in 18.3% of women on RPCA compared with only 5.1% of women with an EA (RR 1.52 95% CI 1.35-1.71, P<0.001).

Hypotension with a systolic blood pressure less than 90 occurred in 6.9% of women on RPCA and 11.6% of women with an EA (RR 0.75, 95% CI 0.57-0.998, P=0.03).

In her presentation, Freeman said that the use of a background infusion of remifentanil was unnecessary because the action of remifentanil is so short.

"There are studies that have used a background infusion, and studies that didn't, and they don't find a difference in pain appreciation scores. And, they see more adverse events and low separation when a background infusion is used," Freeman said.

ZonMW, the Netherlands' organization for health research and development, funded this trial. The authors declared no relevant financial conflicts of interest.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

Accessibility Statement

At MedPage Today, we are committed to ensuring that individuals with disabilities can access all of the content offered by MedPage Today through our website and other properties. If you are having trouble accessing www.medpagetoday.com, MedPageToday's mobile apps, please email legal@ziffdavis.com for assistance. Please put "ADA Inquiry" in the subject line of your email.